a way to tell if the other cylinder thats not on the gun is cut down or not is the serial number on the cylinder will be missing the bottom 3rd of the numbers.
Do numbers match? I've seen were the original matching cylinder would be left alone and a non matching cylinder will be cut.

there getting more and more popular to collect. The Mark VI was the Indiana Jones Gun. I know its a fictitious character but its a nice thing to throw in when you talk about a Webley Mk VI.
Before they really were not worth a ton. In fact my uncle has one that was just given to him back in the 60's. The fact that you have a non-converted cylinder does help but too bad its the wrong one. Your looking at a value of about 450-600. 450.00 someone would jump on it right away.

There are four up for bid on the big gun auction, only one with a bid is one with original cylinder, reblue, sharp looking gun bore 100% grips xlnt. Has two bids, now at $410, four days to go. I concur that actual value is $450-$500.

The problem with that one on the auction is that it is a reblue. These were rust blued guns. Altering the finish to salts blue or cold blue is always a value killer. Original finish would fetch more from a collector. The value I gave is based on blue book +20% to adjust for the current market.
There are guys asking 800+ for them but for that same reason they don't sell. Many sell them as "rare" or "military version". Well they all are military versions and now days they are a little rare to see but were not talking Lugers here.